Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

Framebuilders Thinking about a custom frame? Lugged vs Fillet Brazed. Different Frame materials? Newvex or Pacenti Lugs? why get a custom Road, Mountain, or Track Frame? Got a question about framebuilding? Lets discuss framebuilding at it's finest.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 02-11-12, 08:55 AM   #1
chagzuki
Senior Member
Thread Starter
 
Join Date: Jul 2008
Bikes: Brompton, Dahon Vitesse D5
Posts: 1,867
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
How hard for someone with no framebuilding experience to construct a Brompton fork?

I like folding bikes, however there are aspects of their design that persistently frustrate me. I find myself wanting to redesign them myself.

I've never brazed anything, never sourced lugs, crowns etc.. How tricky would it be and what cost would be involved would in attempting to replicate something like this?:



The geometry is unique: how would I obtain fork blades of the correct length? Would it be easy to find a crown of that flat shape so that the threaded section could be brazed on top (with 1 1/8 steerer)? What problems will likely arise?

The primary reason for doing this would be to have a threadless steerer tube, and then to redesign part of the stem, it's an idea that's been floating round my head for a while now and I figure I ought to get a better idea of the feasibility.
chagzuki is offline   Reply With Quote
Old 02-11-12, 09:24 AM   #2
mudboy
Senior Member
 
mudboy's Avatar
 
Join Date: Sep 2008
Location: Collegeville, PA
Bikes: Ruckelshaus Randonneur, Specialized Allez (early 90's, steel), Ruckelshaus Path Bomber currently being built
Posts: 1,354
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Wouldn't be difficult for someone who's done it before, but not a job for an absolute novice.

However, if all you want to do is replace the steerer, that's more do-able, as the steerer tube is about the easiest piece to braze. Getting it hot enough to remove is another story. And, of course, you'd need to strip the paint off the fork first.
mudboy is offline   Reply With Quote
Old 02-11-12, 10:51 AM   #3
lee kenney
Senior Member
 
Join Date: Dec 2010
Location: B.C.
Bikes: ritcheys{2** rm blizzard Geo elrick drop frame and acollection of parts bikes in waiting
Posts: 186
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
A suggestion , take a look at a" Dursley Pedrerson" design using small dia. tubes , A head set . ,alloy disc brake
lee kenney is offline   Reply With Quote
Old 02-11-12, 10:56 AM   #4
lee kenney
Senior Member
 
Join Date: Dec 2010
Location: B.C.
Bikes: ritcheys{2** rm blizzard Geo elrick drop frame and acollection of parts bikes in waiting
Posts: 186
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Steering tubes, off of a suspension fork ,Bottom and top fixing by current star washer systems, Make your own do a "Instructables"
lee kenney is offline   Reply With Quote
Old 02-11-12, 12:00 PM   #5
chagzuki
Senior Member
Thread Starter
 
Join Date: Jul 2008
Bikes: Brompton, Dahon Vitesse D5
Posts: 1,867
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by mudboy View Post
Wouldn't be difficult for someone who's done it before, but not a job for an absolute novice.

However, if all you want to do is replace the steerer, that's more do-able, as the steerer tube is about the easiest piece to braze. Getting it hot enough to remove is another story. And, of course, you'd need to strip the paint off the fork first.
Is swapping out a steerer a not atypical procedure then? I did a quick search on this recently and I thought I detected a rough consensus that it would weaken the fork too much to be safe? Getting a slightly longer threadless steerer is the primary objective, though I'm also interested in learning about frame construction in general.

Last edited by chagzuki; 02-11-12 at 05:18 PM.
chagzuki is offline   Reply With Quote
Old 02-11-12, 03:48 PM   #6
unterhausen
Randomhead
 
Join Date: Aug 2008
Location: Happy Valley, Pennsylvania
Bikes:
Posts: 14,488
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
most framebuilders will not touch a steerer replacement. There are a few that will splice a new steerer onto the old one. Rody at Groovy has a video somewhere of how he does it, a quick search failed to find it
unterhausen is offline   Reply With Quote
Old 02-11-12, 05:19 PM   #7
chagzuki
Senior Member
Thread Starter
 
Join Date: Jul 2008
Bikes: Brompton, Dahon Vitesse D5
Posts: 1,867
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
If I were to make it from scratch what'd be the best solution for the fork blades? I don't know how it's normally done. . . I'm imagining that in this case I'd source some standard size blades and cut them down. But perhaps this wouldn't make for a clean fit in the crown? The other consideration is that the front hub is 74mm OLD.
chagzuki is offline   Reply With Quote
Old 02-13-12, 12:09 PM   #8
erik c
Senior Member
 
Join Date: Feb 2010
Bikes:
Posts: 114
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I've got a pair of True Temper recumbent fork blades that I'm not particularly attached to, but depending on the length needed I'd probably just look into cutting down regular blades as necessary. Ride is clearly not something that is a big concern judging from the fork in the photo.

I've also cut down a bonded alumnium straight leg mtb fork in the past, if the rake is what you want it isn't that huge a deal, but that doesnt the 74 old issue.
erik c is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 01:48 AM.